1. Field of the Invention
The present invention relates to a drum brake structure for a wheel of an all-terrain vehicle.
2. Description of the Background Art
A drum brake assembly of the related art for use with a rear wheel is shown in the cross-sectional view of FIG. 4. A drum brake assembly 100 comprises a brake base section 101 taken as a brake panel fitted to a side of the vehicle. Brake shoes 103, 103 are fitted in a freely swingable manner via a support shaft 102 to the brake base section 101. A brake drum 105 is spline-fitted to an axle 104 so as to encompass the brake shoes 103, 103 and generate frictional force with the brake shoes 103, 103. A drum cover 106 is fitted to the brake base section 101 for covering the brake drum 105. An O-ring is provided between the brake base section 101 and the drum cover 106. A seal member 111 is provided between a hub 108 spline fitted to a tip of the axle 104. An oil seal 113 is provided between the axle 104 and the hub 108. This prevents the intrusion of rainwater and soil. A wheel 114 is fitted to the hub 108.
The aforementioned technology has the disadvantage that because the brake drum 105 and the hub 108 are spline-fitted to the wheel 104, the drum cover 106, O-ring 107 and seal member 111 are required in order to make a gap waterproof and dust-proof between the brake drum 105 and the hub 108, and the brake drum 105 itself. This means that the number of parts is substantial and the number of steps required to assemble the drum cover 106, O-ring 107 and seal member 111 increases. Further, the structure surrounding the drum brake is such that the hub 108 is arranged on the outside of the brake drum 105 and the number of parts is therefore substantial.
The brake drum 105 and the hub 108 are heavy, and this is a cause of an increase in the weight of the vehicle, although it would be preferable for the vehicle to be light in weight. With this structure, it is difficult for heat generated at the drum brake 100 to escape to the outside due to the drum cover 106.
It is therefore an object of the present invention to provide a drum brake structure for a wheel of an all-terrain vehicle which reduces the number of assembly steps by decreasing the number of parts, improving vehicle handling by making the vehicle lighter in weight, and improving heat dissipation.
In order to achieve the aforementioned object, a drum brake structure for a wheel of an all-terrain vehicle is provided such that the wheel may be directly fitted to the brake drum. A fin for dissipating heat is provided at the outer peripheral surface of the brake drum. A seal member is fitted to an opening edge of the brake drum. A plate for abutting a lip of the seal member is fitted to a brake panel which is fitted at a vehicle side. A brake shoe is supplied in a space formed by the brake panel and the drum.
The seal member is fitted to the edge of the opening of the brake drum, and the lip of this seal member abuts with the plate fitted to the brake panel which is fitted to a side of the vehicle so that the drum brake is sealed.
By fitting the wheel directly to the brake drum, the vehicle width can be made narrow compared to, for example, the fitting of a wheel to a hub separate from the drum. Also, the drum brake is housed within the wheel, and the vehicle can be lighter in weight since heavy parts such as the hub can be omitted. Also, because a fin is provided at the outer surface of the brake drum, heat dissipation of the drum brake is improved.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.